Evaporating apparatus



April 2, 1935. R. .1. `SERF'AS 1,996,526

EVAPORATING APPARATUS Filed Aug. 6, 1934 A Zorn Patented Apr. 2, 1935 UNITED STATES Price Claims.

This invention relates to evaporators and evaporating processes for use particularly in pulp mills, sugar mills, milk drying apparatus, chemical apparatus etc., although capable of use in 5 evaporating all manners of liquids.

It is the general object of the invention to provide a novel and improved evaporator and a novel and improved evaporating process, which will operate with great economy and emciency in lO evaporating liquids of all kinds.

The 'objects and advantages of the invention will more fully appear from the following description, made in connection with the accompanying drawing, wherein like reference characters refer to the same or similar parts throughout the various views, and, in which,

Fig. 1 is a more or less diagrarmnatic view in side elevation illustrating an embodiment of my evaporating apparatus, the tank of the apparatus being shown in vertical section; and

Fig. 2 is a detail in enlarged scale showing in vertical section certain of the parts.

In accordance with the invention, there is provided a large tank 9 preferably made in sections, each section being equipped with one or more doors 4, so that ready access may be had to the interior of the tank as occasion demands. In the lower portion of the tank there is provided a steam chest 5, the portion of the tank below the steam chest forming a chamber 6. Open ended tubes 'I run upwardly through the steam chest 5 and they communicate at their lower ends with the chamber 6 and they communicate at their upper ends with the space in the tank immediately above the chest.. Above the steam chest 5 a plurality of horizontal liquor holding trays 8 and 9 are provided in the tank 9. The trays 8 and 9 are disposed in spaced superimposed relation, the trays 9 being alternated relative to the trays 8 from the upper part of the tank downwardly. The trays 9 are secured to the tank 8 by means of brackets I0 and the peripheral edges of the trays 8 are centrally spaced from the walls of the tank to form passages I I between these edges and the walls of the tank. The peripheral edges of the trays B are provided with upstanding flanges of short length. The trays 9 have their peripheral edges attached to the side walls of the tank 3 and in the form shown these trays are provided with central openings forming passages I2. The edges of the trays 9 adjacent the passages I2 are provided with upstanding flanges of the same height as the flanges of the trays 8.

Mounted in openings in the bottoms of the various trays 8 and 9 are a multiplicity of Short open ended tubes i8, best shown in Fig. 2. These tubes extend upwardly from the bottoms of the trays to points spaced somewhat below the upper edges of the flanges of the trays to which the tubes are secured. Caps I4 of inverted cup- 5 shape extend over the upper ends of the tubes I3 and these caps are of considerably greater diameter than the tubes I8 and they may be conveniently lattached to the tubes by means of apertured collars I5 attached to the tops of the l0l caps, projecting downwardly therefrom and having lower portions embracing the upper'portions of the tubes I3. The collars I5 are each provided with one or more inturned lugs I5@ which overlie the upper edge of the tube I3 to which the 'l5 particular collar is attached. The top of each cap I4 is spaced above the level of the upper end of its tube I9 and a small aperture Ia is formed in the top of the cap immediately above the tube.

A liquor supply pipe I8 is mounted in the upper portion of the tank 3 and it has a discharge mouth I6a located above the uppermost tray `8 to discharge thereto. Connected to the pipe I8 is a pipe I1 equipped with a valve I8 and connected 26 to the discharge outlet of a pump I9, this pump being driven by any suitable source of power (not illustrated). There is provided a large storage tank 20 within which the liquor to be evaporated may be held. A pipe 2i mounted in the bottom 30 of the tank 20 and equipped with a valve 22 runs downwardly from the tank and is connected to a pipe 23 which, in turn, is connected tothe inlet port of pump I9. A branch pipe 2Q equipped with a. valve 25 is connected at its lower end to 35 pipe 2l above the valve 22 and it is connected to pipe I8 at its upper end. A pipe 28 equipped with a valve 21, is connected to pipe Il between the discharge outlet of pump I 9 and valve I8 and this pipe 28 discharges into a rotary drier 28.

The pipe 29 is connected at one end to the lower part of the tank 3 to communicate with the chamber 6 and it runs directly to the inlet port of the pump I9, the pipe being provided with a valve 29. An inverted U-shaped pipe has one small 45 arm 30a connected to the pipe 23 ahead of the valve 29 and another large arm 30h connected to the pipe 23 between the valve 29 and the pump I9. The arm a is equipped with a valve 8l.

'I'he U-shaped pipe 80 projects upwardly to a 50 point above the level of the steam chest 5 in tank 3. i. e. to the level that it is desired to maintain liquor in the tank 3, and there is connected to the upper portion of the pipe 90, between the arms thereof, an upwardly projecting pipe 92 open at 55 its upper end to the atmosphere and equipped with a valve 52. Between the valve 3| and the pipe 32 there is provided a back flow check valve 33 in the U-pipe 30.

A drain pipe 34 equipped with a valve 35 is connected to the bottom of the tank 3. A flanged vapor outlet port 36 is provided in the top of the tank 3 and connected at one end to this outlet port is a tube 31 for carrying oi the vapor from the tank. This tube 31 runs into a condenser 38 or to a vacuum pump, (not illustrated). The condenser 38 is not shown in detail, but it may be provided with a pipe 39 for carrying off the condensed liquor.

It is desirable at times to drain all the various trays 8 and 9 and for this purpose the various trays are provided with vertical aligned apertures through which a rod 40 extends. The walls of the trays about the apertures form valve seats with which valves 4| mounted on rod 4I) cooperate. The upper portion of the rod 40 extends through a packing gland 42 in the top of the tank 3 and is pivotally connected to a lever 43 fulcrumed on a bracket 44 attached to the top of the tank 3. By operation of the lever 43, it will be seen that all the various valves 4| may be simultaneously raised from their seats to permit drainage of whatever liquor may be held within the trays 8 and 9.

A water glass 45 for determining the liquid level within the tank 3 is connected at its lower end to the tank below the steam chest 5 and is connected at its upper end to the tank in spaced relation above the top of the steam chest. A steam supply pipe 46 equipped with a valve 41 supplies steam to the chest 5 and a pipe 48 equipped with a valve 49 is connected to the lower part of the steam chest and will carry oil condensed steam (water), and cooled steam from the chest. A steam pressure gauge 50 is connectedto the pipe 46, while another pressure gauge 5| adapted to register the lack of pressure or vacuum in tank 3 is connected to the tank preferably at about the position shown.

Operation When it is desired to evaporate liquor contained in the tank 20, it is rst necessary to pump the requisite amount of liquor into the tank 3. Steam will be supplied to the steam chest 5 through the supply pipe 46 controlled by valve 41 and condensed water and some steam will be discharged from the steam chest through the discharge pipe 48 controlled by valve 49. By observation of the gauge 58 and manipulation of the two valves 41 and 49 the pressure of steam within the chest may be regulated. Valves 35, 29, 3|, 52, 21 and 25 will be closed and valves 22 and I8 will be opened and the pump I9 will be placed in operation. The pump I 9 will then draw liquor from the tank 20 through pipe 2| and the right hand part of pipe 23 into the pump and force this liquor upwardly through pipe |1 and pipe I8 to discharge through the mouth I6a. into tank 3 above the uppermost tray 8. The liquor discharged from the mouth |6a will rst drop into the uppermost tray 8 and accumulate there until the level of liquor within the tray rises above the upper ends of the tubes I3 mounted in this tray. The liquor will then overow into the numerous tubes I3 and will drop downwardly through the tubes in small drops or ne streams to the uppermost tray 9 below the tray 8. It will, of course, pass through the air within the tank 3 between the two uppermpst trays 8. and 9 in nely divided form. Similarly, the liquor will accumulate in the uppermost tray 9 until its level within this tray rises above the level of the upper ends of the tubes I3 mounted on the tray 9 and the liquor will then overflow into the tubes I3 on the uppermost tray 9 and pass on downwardly in iinely divided form through the air in the tank 3 to the next lower tray 8. In this manner all the trays 8 and 9 will be filled until the liquor overflows from the lowermost tray 9. The liquor will then rst iill the chamber 6 and then fill the tubes 1 through the steam chest 5 until the level of liquid, as determined by examination of the water glass 45,*reaches about the point shown or to approximately the level of the upper part of the U-pipe 30.

In connection kwith the action of the tubes |3 in transmitting the liquor from one tray to another, it should be noted that before the liquor level in any tray reaches a point above the upper ends of the tubes I3 mounted in that tray,

the lower edges or skirts of the caps I4 will be immersed in the liquor so that the upper ends of the tubes |3 will be sealed from the free passage of air or vapor upwardly from below the tray through these tubes. The apertures |4a are provided in the caps I4 to prevent siphoning action when the liquor first starts to overflow the upper ends of the tubes I3. After the trays 8 and 9 are once lled, the level of liquor in these trays will be maintained automatically.

After the tank 3 has been lled with liquor, as described, the valve 22 will be closed and valve 29 will be opened. The liquor in the tank 3 will now be recirculated from the bottom of the tank to the top of the tank. The pump I9 will draw liquor from chamber 8 through pipe 23 and will force the same through pipe I1 and pipe I6 to discharge from the mouth Ilia. Finely divided particles of liquor will thus continuously drop from higher trays 8 or 9 in the tank 3 to lower trays 9 or 8. The steam chest 5 in the lower part of the tank will heat up the liquor in the tubes 1 and above and below the steam chest. This liquor will begin to vaporize through boiling action and vapor rising from the bodi7 of liquor in the lower part of the tank will pass upwardly in a tortuous path between, through and about the various -trays 9 and I0. The Yvapor below the lowermost tray 9 will pass upwardly through thelpassage I2 in this tray after imparting some of its heat to the bottom of the tray. The vapor then will strike the bottom of the lowest tray 8 and movelaterally toward the walls of the tank 3 and pass on upwardly through the passages between the lowermost tray 8 and the side walls of the tank. Then the vapor will pass through the passage I2 in the next higher tray 9 and so on until it reaches the top of the tank 3. During its travel upwardly, the.

vapor not only heats the various trays 8 and 9 to impart-heat to the liquor contained in these trays, but it also comes into intimate contact with the ne particles of liquor dropping downwardly from one tray to another and heats the liquor in this manner. Accordingly, the liquor contained in the various trays 8 and 9 becomes highly heated and the liquor dropping down from the lowermost tray 9 to a point above the steam chest 5 is highly heated so asv to readily -vaporize. The vapor .passing upwardly through the drum must follow the tortuous path indicated by the arrows in Fig. 1, as it cannot readily pass upwardly through the various tubes |3 due to the liquid seals over the upper ends ofthese tubes formed by the caps I4, the skirts of which are immersed in the liquor held within the trays.

The vapor rising to the top of the tank 3 passes out through the tube 31 into the condenser 38 or equivalent vacuum pump. Ii' the condenser 33 is used, the vapor will be condensed into liquid form and drawn oil through the pipe 39 and this action will create a partial vacuum in the tube 3l and in the tank 3 to assist in carrying oil the vapor and to reduce the necessary temperature required for vaporization of the liquor. As the quantity of liquor in the tank is depleted through vaporization of the water in the liquor, additional quantities of fresh liquor from the tank 20 may be introduced into the tank 3 by partially opening the valve 25. Some liquor will then be drawn through pipe 24 from the bottom of the tank to be introduced with the main body of liquor rccirculatecl through thc pipe I6 into the tank.

When the liquor has been suillciently concentrated in tank 3. the valve I3 may be closed and valve 21 opened whereupon the pump I3 will draw oil the liquor from the chamber 3 through pipe 23 and force this liquor through the lower part of pipe I1 and pipe 23 into the rotary drier 23 or elsewhere.

It is highly desirable in certain uses that after the evaporator has been once set in full operation and the liquor therein has been brought to the proper concentration, that a certain quantity of the concentrated liquor be constantly drained oil from the tank 3 and that a certain quantity of fresh or unevaporated liquor be constantly supplied to the tank 3, so as to maintain the concentration of liquor drawn oi! the same. This can be readily done with the present apparatus. The valve 23 and valve 22 will be closed and valves 3l and 52 will be opened. Valve I3 will be partially closed, valve 21 partially closed and valve 25 partially closed. When the level of liquor in the lower part oi the tank 3 rises to a point above the top of the U-pipe 30, liquor will ow by gravity from the tank 3 through the left portion of pipe 23, arm 30a and the upper part of the U-pipe 30 into the large arm 30h. A siphon action through the U-pipe will not take place due to the fact that the pipe 32. when the valve 32 is open. is open at its upper end to the atmosphere. Back ow of air to the tank 3 through the arm 30a of the U-pipe is prevented by reason of the back ow check valve 33. The level of liquor in the lower part of the tank 3 will be maintained by the U-pipe 30 at approximately the point indicated in the drawing. The pump I9 will draw oil the liquor in the arm 30h through the pipe 23 and the pump will force some of this liquor, which it should be stated is highly concentrated, through thepipe 26 to the rotary drier 28. the setting of the valves 2l and I3 determining what quantity of this liquor will be carried off to the drier. and what quantity will be recirculated to the tank 3. The pump I9 will force a portion of the liquor through the pipe I1 and pipe IB into the tank 3 and along with this recirculated and concentrated liquor a quantity of undehydrated liquor will pass over` to the tank 3 from the tank 20 by passage throughthe pipe 24 and pipe I6. The quantity of undehydrated liquor admitted will be determined by the setting of the valve 25. By proper adjustment oi the three valves 21, I3 and 25, the apparatus can be kept in continuous .operation so that a definite quantity of highly concentrated liquor can be drawn oil to the drier 23, a definite quantity of fresh liquor may be fed to the tank 3, the liquor level in the bottom of the tank 3 may be maintained substantially constant at a point approximately level with the upper part of U-pipe 30 for most eihcient evaporating action and the liquor drawn oil* will have a relatively constant degree of concentration.

Easy access to various parts of the tank 3 may be had through the various doors 4. When it is desired to clean out the tank 3. the left end of lever 43 may be depressed to raise the various valves 4I from their seats and the liquor in the various trays 89 will then drain to the bottom of the tank 3. By opening the valve 35, the entire tank may be emptied.

It will, oi course, be appreciated that the various trays 8 and 9 may be differently constructed and arranged for causing a tortuous circulation of the vapor through, about and around these various trays. It will also be understood that in place of the tubes I3 and caps I4, other means having the equivalent function oi' the tubes and caps may be provided.

It will be seen that a most eillcient and economical evaporating apparatus and evaporating process has been provided. The heat of the vaporized liquor is utilized for preheating the liquor before it is carried to a point about the steam chest 5. The entire evaporating process may be carried out with the simple apparatus shown without requiring evaporation by several stages as is customary.

It will, of course, be understood that various changes may be made in the form, details. arrangement and proportions of the various parts of my apparatus and that various changes may be made in the steps of my evaporating processes without departure from the scope of the present invention, which, generally stated, consists in the matter shown and described and set forth in the appended claims.

What is claimed isz- 1. An evaporator having in combination, a tank, means for supplying the liquor to be evaporated at the upper part of the tank, heating means in the lower part oi the tank, means for withdrawing vapor from the upper part oi the tank. a plurality of trays mounted in superposed spaced relation in the tank above said heating means. said trays being constructed and arranged to permit of a tortuous circulation of vapor upwardly from the lower part of the tank through and about said trays, a multiplicity or short tubes carried by each tray and projecting therethrough, said tubes having open upper ends spaced above the bottoms of the trays in which they are mounted, downwardly flanged caps attached to the upper ends of said tubes and sealing by liquid the passage of vapor upwardly through the same while permitting the overow of liquor from said trays through said tubes, the uppermost trays receiving from said supply means and the liquor overilowing through said tubes passing in inely divided state from upper trays to lower trays.

2. An evaporator having in combination, a tank, a steam chest in the lower part of the tank, said tank forming a liquor containing chamber below said steam chest, open ended tubes running upwardly from said chamber through said steam chest, a plurality of trays mounted in superposed relation in said tank above said steamchest. there being vapor passages through said trays permitting a tortuous travel of vapor upwardly through and about said trays, a multiplicity of small conduits mounted in each tray and having admission openings spaced above the bottom of the tray,

' means sealing said admission openings to prevent the passage of vapor upwardly through said conduits while permitting the overflow of liquor from said trays through said conduits, means for withdrawing liquor from said chamber, means for supplying liquor to said tank,` above the uppermost tray and means for withdrawing vapor from said tank above the level of the uppermost tray.

3. An evaporator having in combination, a tank, heating means in the lower part of said tank, means for supplying liquor to be evaporated at the upper part of the tank, means for drawing oir vapor from the upper part of the tank, a

y plurality of trays mounted in superposed spaced relation in the tank above said heating means, said trays being constructed and arranged to permit of a-tortuous circulation of vapor upwardly from the lower part of the tank through and about said trays, a multiplicity of small overflow conduits mounted in and extending through the respective trays and having admission openings located above the levels of the bottoms of l the respective trays in which they are mounted,

the uppermost tray receiving from said supply means and the liquor overflowing through said conduits, passing from upper trays to-lower trays, liquid seals for the admission openings in said conduits permitting the passage of liquor from said trays to said admission openings but preventing the passage of vapor upwardly through said conduits, and means for drawing oi liquor from the lower part of said tank.

4. An evaporator having in combination, a tank, heating means in the lower portion of said tank, a portion of said tank below said heating means comprising a liquor containing chamber, a plurality of trays mounted in superposed relation in said tank above said heating means, there being vapor passages through said trays permitting a tortuous travel of vapor upwardly through and about said trays, a multiplicity of small conduits mounted in each tray and having admission openings spaced above the bottom of the tray, means sealing said admission openings to prevent the passage of vapor upwardly through said conduits while permitting the overflow of liquor from said trays through said conduits, means for exit of liquor from said chamber, means for supplying liquor to said tank above the uppermost tray and means of xit for vapor from said tank above theA level of the uppermost tray.

5. The structure defined in claim 4 and the uppermost portion of each of said conduits being provided with a restricted relief vent to prevent Siphon action in said conduits.

RALPH J. SERPAS. 

